Metal forming method and apparatus

ABSTRACT

A conventional press of high capacity has three sets of dies therein to form an ironing board in three stages, blank and draw in the first stage, flange embossment and pre-curl in the second stage, and finish curl in the third stage. Co-operating slidemounted dies and rocker-mounted dies are provided in the second stage and operated by cams on the press ram-mounted section of the die set for simultaneously embossing and pre-curling the skirt portion around the entire perimeter of the part. In the third stage, a locating cavity with a bottom wall of circular cross section receives the pre-curled lower edge of the skirt and forms the finished curl thereon as the press closes.

United States Patent Lamm [is] 3,685,340 [4 1 Aug. 22, 1972 [54] METAL FORMING METHOD AND APPARATUS [72] Inventor: Merritt Otis Lamm, Muncie, Ind.

22 Filed: June 15, 1970 21 Appl. No; 46,099

9/1943 Pearson et al. ..72/399 4/1940 l-linsdale ..72/355 Primary Examiner-Richard J. Herbst Attorney-Woodard, Weikart, Emhardt & Naughton ABSTRACT A conventional press of high capacity has three sets of dies therein to form an ironing board in three stages, blank and draw in the first stage, flange embossment and pre-curl in the second stage, and finish curl in the third stage. Co-operating slide-mounted dies and rocker-mounted dies are provided in the second stage and operated by cams on the press ram-mounted section. of the die set for simultaneously embossing and pre-curling the skirt portion-around the entire perimeter of the part. In the third stage, a locating cavity with a bottom wall of circular cross section ,receives the pre-curled lower edge of the skirt and forms the finished curl thereon as the press closes.

11 Claims, 7 Drawing figures 124 lz I23 12/ PATENTED M1922 1912 saw 1 ur i3 INVENTOR MERR/TT OTIS LAM/vi ATTORNEYS (Wm, wage/Mi, M g 77% METAL FORMING METHOD AND APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to press work, and more particularly to a method of forming an embossed flange with a curled edge around the entire perimeter of a product of irregular shape, and the dies for accomplishing the same.

2. Description of the Prior Art Various prior art procedures are known for providing beads on the rims of products of regular shapes. Examples are on cylindrical cans, lids, and various types of wheels. Nevertheless, there has been a need for simple ways and means of providing a complete curl or bead at the edge of a flange extending around the entire perimeter of a part of substantial size. The present invention meets this need.

Summary of the Invention In a typical embodiment of the invention, a press is provided with die sets for making a product of irregular shape by formation thereof in three stages. In the first stage a flange is drawn to provide a skirt around the entire perimeter of the product. In the second stage, the

perimetrical skirt is embossed and pre-curled at its lower margin by a combination of rocking and slidemounted dies. In the third stage the lower margin is finish curled in a groove against which it is forced by the press ram.

Brief Description of the Drawings FIG. 1 is a front elevational view of a press having a three stage die set therein.

FIG. 2 is an enlarged schematic illustration showing the cross section of the part at the completion of each of the three stages of operation thereon.

FIG. 3 is a plan view of the second stage lower die section, with the slides and rockers in skirt forming condition, but the top of the ironing board is omitted in order to show die arrangement.

FIG. 4 is a section at line 4-4 in FIG. 3 and viewed in the direction of the arrows, showing details of a slide and rocker rail.

FIG. 5 is a plan view of the third stage lower die section, with the top of the ironing board omitted in order to show the die arrangement and lift rails.

FIG. 6 is a section taken at line 66 in FIG. 5 and viewed in the direction of the arrows.

FIG. 7 is an enlarged fragmentary portion of the plan view of FIG. 3 showing embossments in the dies of the second stage.

Description of the Preferred Embodiment Referring now to the drawings in detail, the press itself is conventional. It includes a bed 11 and a ram 12 drivable downward and returnable upward by conventional mechanism connected to the crank shaft 13. A bolster or combination of bolsters or other structure 14 is affixed to the bed and three die sets are provided, each having a lower section affixed to the bolster. Thus there are provided the three stages employed for the complete formation of an ironing board.

In the first stage, the die shoe 16 is affixed to the bolster and has the lower die 17 affixed thereto. A plurality of die guide pins 18 is provided near the left hand edge of the die shoe, extending in a row from the front of the press to the back of the press. As an'example, four such die pins may be employed. The die line (stock feed line) is at 19, and the stock may be moved into the first stage from behind the press by appropriate feed means at that location.

Referring further to the first stage, a ram adapter 21 is affixed to the ram, and has a punch holder 22 affixed to the underside thereof. The upper die 23 is affixed to the punch holder 22.

Referring now to the second stage die set, the lower die shoe is provided at 26 and rocking die blocks are provided at 27, 28, and 29, as will be described more fully hereinafter.

The upper section die set of the second stage die set includes the upper die 31 mounted to the holder 32 and ram adapter 33. Cams 34 and 36 are mounted to the holder 32 at the sides of the die, and a cam 37 is mounted at the end of the die.

In the third stage, the lower die 38 is affixed in the lower die shoe 39 and a guide pin 41 is mounted in the lower die shoe. Just as in the first stage, a die pin guide bushing 42 is mounted in the upper die section to the holder 43 mounted to the ram by'suitable adapter plate structure 44. The upper die is provided at 46. Appropriate transfer means are provided, including horizontal rail 47 for movement of carriages along it for transfer of the part from the first and second stages to the second and third stages, respectively.

Referring now to FIG. 2, the cross sectional shape of the blank as formed andpierced in the first stage is shown at 48, wherein there is a flat. central top portion v therefor to lift the part from the die of the first stage after the blanking and drawing operation is completed.

The central portion of FIG. 2 shows the part in the second stage wherein the central top portion 49 remains the same in appearance, but a pre-curl at 54 is provided along the lower marginal edge around the entire perimeter of the part. Also, an embossment is provided in the skirt 5] as shown at 56. The embossment is actually a series of rectangular bosses horizontally spaced and spaced along the skirt throughout the perimeter of the part. The lifter is shown at 57 with the lift plate 58 mounted to the upper end of the lifter rod 59.

The right-hand portion of FIG. 2 shows the part in the third stage with the finished curl completed at the lower marginal edge as shown at 61. The view also shows the two pistons and associated piston rods and lifter rails which extend throughout substantially the entire length of the lower die as shown better at 62 in FIG. 5.

Referring now to FIG. 3, along with FIG. 4, the dies 27, 28, and 29 are shown along with a die 30. The two dies 27 and 28 are in the form of elongated rails having inwardly facing die faces 63 and 64, respectively. It can be seen that these form a configuration of elongated generally parallel horizontally spaced sides blended into the converging elongated sides, typically the shape of conventional ironing boards. The die face 66 of the die 29 faces inwardly and has the curved end shape for the ironing board. Similarly the die face 67 on the die 30 has the inwardly facing surface to form the rear end of the ironing board. The rail 27 has a pair of downwardly projecting arms 68 (FIG. 4) at opposite ends thereof received on journal pins 69 mounted in pivot blocks 71 affixed to the die shoe 26 so the rail 27 can pivot (rock) on the horizontally extending axis 73.

The front end die shoe is similarly mounted in a rocking manner on the pair of pivot pins 74 to enable rocking of this die shoe on a horizontal axis 76. Similarly the rear end die shoe 30 is mounted on a pair of pivot pins 77 to the die shoe for rocking on the pivot axis 78. Accordingly, each of the dies 27, 28, 29 and 30 is capable of rocking from a position such as shown by the dotted outline 27A in FIG. 4, when the die set is open, to a position such as shown by the solid lines in FIG. 4 when the die set is closed. In order to move these rocking dies from the closed position to the open position, and continuously urge them in the opening direction, appropriate return springs and rods are employed such as the return springs 79 each having one end engaging the spring rest pedestal .81, and the other end engaging a washer on a nut 82 received on a rod 83 secured in the rocking die 27. These springs constantly urge the die 27 in the direction of the arrow 86 (FIGS. 3 and 4).

In addition to the rocking dies, having faces formed to provide the desired overall exterior shape of the ironing board skirt, as well as the embossments and precurl therein, there are inner dies 87, 88, 89, and 90. These have outer faces matching the inner faces of the rocking dies to cooperate therewith in forming the embossments and precurl. Each of these inner dies is mounted on one or more slides. The end dies 89 and 90 are mounted on the slides 91 and 92, respectively. The dies 87 and 88 are mounted on the slides 93 and 94, respectively. Note that there are three of each of the slides 93and slides 94. Details of these slides are better shown in FIG. 4 wherein the slide 93 is slideably mounted on the top surface 96 of a groove in the die shoe 26 and is normally urged inwardly by a return spring 97. As shown in FIG. 4, the slide is in the dieclosed position as shown by the solid outline, and the dotted outline 87A shows the die in the open position.

As shown in Fig. 4, the die 27 has an inclined cam follower face 98 thereon, as well as another inclined cam follower face 101thereon. These cam follower faces are co-operable with cam faces of the cam member 34 and, as better shown in FIG. 3, just as there are three slides 93 for the die 87, so are there three cam follower faces 98 for the rocking die 27 Each of these faces is aligned with one of the three slides 93 so that only three cam members are needed to simultaneously operate the rocking die 27 and the slide-mounted die 87. The same type of construction is provided for the rocking die 28, and the end rocking dies 29 and 30, the latter having only one cam for operation thereof.

As further shown in Fig. 4, in addition to the two end cam members and the six side cam members, the upper die assembly may be mounted to the upper die shoe 32, as indicated at 31, and includes a spring loaded pressure pad 102 urged downwardly by the springssuch as at 103, withithe downward limit of travel determined by abutting engagement between the flanges 104 and 106.

Referring now to FIGS. 5 and 6, the upper die 46 is mounted to the holder 43. In the lower die assembly, a pressure pad 108, urged upwardly by a set of coil springs, one of them being shown at 109, has a die 111 aflixed thereto. A plurality of these dies is shown.

around the inner perimeter of the ironing board skirt as shown in Hg. 5. The die 38, afiixed to die shoe 39, is provided with the chamfered lead-in face 112 to cooperate with the die 111 to provide a locating cavity at 113 when the die set is opened. The die 38 also has the semi-circular groove 114 at the bottom of the locator cavity for providing the finished curl operation on the part as shown at 61 when the die set is closed.

One of the lift rails is shown at 62 atop a connecting rod 116 driven by the pneumatic cylinder 117. An elongated insert may be provided at 118 to receive indentations or other surface features of the ironing board top 49 in this third stage die set.

In FIG. 7, there is shown the horizontally spaced relation of the embossments formed in the skirt 51 in the second stage dies.

OPERATION piece. The press is closed and the blank shaped like an ironing board is blanked from the sheet and drawn to provide the skirt entirely around its perimeter. The

cross sectional shape is shown in FIG. 2 at the left.

Then the press is opened and the piece is transferred from the first stage to the second stage by the transfer means, and a new sheet is placed in the first stage.

As the press closes, the pressure pad 102 engages the stock and urges it against dies 87, 88, 89 and 90. Cam face 121 of cam member 34 engages follower face 98 of die 27 and begins to rock the die inwardly. Corresponding cam faces of the other cam members rock the other rocking dies inwardly. Cam face 122 of cam member 34 engages face 99 of slide 93, urging the slide outwardly in the direction of arrow 86. The other cam members urge the corresponding slides outwardly in like manner. Thus the skirt forming faces of dies 27 and 87 cooperatively engage skirt 51 and form the bosses 56 therein and the beginning of a reverse curl (pre-curl 54) along the lower margin thereof. (FIG. 2 and 4). The same operation takes place around the perimeter of the part.

When the press opens return cam face 123 of the cam member 34, engaging face 124 of slide 34 forces the slide inwardly, opposite the arrow 86, to provide a positive return of the slide, aiding the spring 97, until the slide has returned one eighth inch, for example. Then the lower edge 126 of return face 123 clears the upper edge of face 124, and edge 126 moves up in space 127 along face 128. The spring 97 continues return of the slide as cam face 122 moves up along face 99. Then lifters 58 lift the part for transfer to the third station by transfer means, as the transfer means transfer a newly formed sheet in stage one to stage two.

When the part arrives at the third stage, it is deposited on the elevated pad 108 and dies 111 mounted thereon. The pre-curled edge 54 is disposed in the locating cavity 113, positioning being aidedby the ramp 112 around the entire perimeter of the cavity. Then the press is closed.

As the ram descends the lower edge of the pre-curled portion engages the semi-circular groove 114 and further descent of the ram continues curling portion 54 in the groove until it assumes three quarters of a circle as shown in FIG. 6 when closure of the press is complete. At this point, the pad 108 will have been forced downward against the resistance of the springs, a distance of about three lengths of an inch, for example, thus keeping the piece properly located as the finish curling is accomplished simultaneously around the entire perimeter of the part.

After the press is opened, rails 62 are lifted and the part is ejected from the third stage, usually through the front of the press. Then the rails are lowered, and the transfer means shifts pieces from the first and second stages, to the second and third stages, respectively.

The invention claimed is:

1. In forming apparatus for sheet stock, the combination comprising:

a first die section securable to a press;

a plurality of slides on said first die section, each of said slides having a die thereon disposed inwardly with respect to a perimetrical skirt portion of a part to be formed thereon and movable outwardly against said skirt portion;

a plurality of rockers on said first die section, each of said rockers having a die thereon having an inner face formed to mate with an outer face of one of said dies on said slides, said rockers being rockable inwardly to move said dies thereon against said skirt portion; I

and cam follower means operable in response to movement of a press ram to cause cooperating engagement of said slide mounted dies and said rocker mounted dies with said skirt portion to form said skirt portion, said cam follower means including a cam follower on each of said rockers and a cam follower on each of said slides, the followers on said slides being disposed outwardly with respect to said rockers.

2. The combination of claim 1 wherein:

said dies are shaped to curl a lower edge portion of said skirt portion upon said cooperating engagement.

3. The combination of claim 1 and further comprisa second die section aligned with said first die section and movable to cooperate with said first die section in the formation of a part therein;

cam means on said second die section and engageable with said cam followers on said slides and rockers during closure of said die sections to drive said slide mounted dies and said rocker mounted dies into skirt forming engagement with said skirt portion.

4. The combination of claim 3 and further comprisslide return springs urging said slides inwardly toward a point between them,

and rocker return springs urging said rocker mounted dies outwardly from a point between them.

5. The combination of claim 3 wherein:

said dies are shaped to pre-curl a lower edge portion of said skirt portion upon said cooperating engagement,

said combination further comprising;

a third die section securable to a press bolster;

a first die on said third section and having a skirt confining wall, and a curling groove disposed adjacent to said wall and receiving at a reception point adjacent said wall the pre-curled lower edge portion of said skirt portion of a part formed in said first die section, said groove extending from said reception point inwardly to a termination farther from said wall;

and a fourth die section aligned with said third die section and movable to cooperate with said third die section to force said pre-curled edge portion further into said groove toward said termination to finish curl said edge portion.

6. In forming apparatus for sheet stock, the combination comprising:

a first die section securable to a press;

a plurality of slides on said first die section, each of said slides having a die thereon disposed inwardly with respect to a perimetrical skirt portion of a part to be formed thereon and movable outwardly against said skirt portion;

a plurality of rockers on said first die section, each of said rockers having a die thereon formed to mate with one of said dies on said slides, said rockers being rockable inwardly to move said dies thereon against said skirt portion;

cam follower means operable in response to movement of a press ram to cause cooperating engagement of said slide mounted dies and said rocker mounted dies with said skirt portion to form said skirt portion;

a second die section aligned with said first die section and movable to cooperate with said first die seca first die on said third section and having a skirt con- I fining wall, and a curling groove disposed adjacent to said wall and receiving at a reception point adjacent said wall the pre-curled lower edge portion of said skirt portion of a part fonned in said first die section, said groove extending from said reception point inwardly to a termination farther from said wall;

a fourth die section aligned with said third die section and movable to cooperate with said third die section to force said pre-curled edge portion further into said groove toward said termination to finish curl said edge portion;

a press having a bolster and a ram,

said first and third die sections being secured to said bolster,

said second and fourth die sections being secured to a common plate drivable by said ram toward said bolster,

fifth and sixth die sections secured respectively to said bolster and said common plate and co-operable to punch a blank from a sheet and draw a perimetri'cal skirt portion thereon during movement of said press ram;

whereby as said ram moves toward said bolster, said sixth, second, and fourth die sections are closed with said fifth, first and third die sections respectively providing first, second and third stages of forming operations on a part transferable from said first to second and then to third stages, the first operation being a blank and skirt drawing operation, the second being a skirt dimpling and pre-curling operation, and the third being a finish curling operation.

7. The combination of claim 1 wherein:

the dies of said slides are disposed in a pattern with skirt forming faces thereof defining a shape having sides with elongated spaced generally parallel portions and elongated portions converging toward a rounded end at one end, and a generally straight end at the other end.

8. The combination of claim 7 wherein:

there are at least four of said'slides, one on each side and one on each end, the skirt forming faces thereof defining the shape of an ironing board.

9. The combination of claim 8 wherein:

there are at least four of said rockers, one on each side and one on each end.

10. The combination of claim 1 wherein:

the dies of said slides are disposed in a pattern with skirt forming faces thereof defining a non-circular shape and having embossments therein spaced along the length thereof.

11. The combination of claim 3 wherein said cam means include a cam member disposed between the cam follower on one of said rockers and the cam follower on one of said slides, said cam member being operable during closure of said die sections to drive away from each other the said cam followers between which said cam member is disposed and thereupon effect said co-operating engagement of the die mounted to said slide and the die mounted to said rocker with said skirt portion. 

1. In forming apparatus for sheet stock, the combination comprising: a first die section securable to a press; a plurality of slides on said first die section, each of said slides having a die thereon disposed inwardly with respect to a perimetrical skirt portion of a part to be formed thereon and movable outwardly against said skirt portion; a plurality of rockers on said first die section, each of said rockers having a die thereon having an inner face formed to mate with an outer face of one of said dies on said slides, said rockers being rockable inwardly to move said dies thereon against said skirt portion; and cam follower means operable in response to movement of a Press ram to cause cooperating engagement of said slide mounted dies and said rocker mounted dies with said skirt portion to form said skirt portion, said cam follower means including a cam follower on each of said rockers and a cam follower on each of said slides, the followers on said slides being disposed outwardly with respect to said rockers.
 2. The combination of claim 1 wherein: said dies are shaped to curl a lower edge portion of said skirt portion upon said cooperating engagement.
 3. The combination of claim 1 and further comprising: a second die section aligned with said first die section and movable to cooperate with said first die section in the formation of a part therein; cam means on said second die section and engageable with said cam followers on said slides and rockers during closure of said die sections to drive said slide mounted dies and said rocker mounted dies into skirt forming engagement with said skirt portion.
 4. The combination of claim 3 and further comprising: slide return springs urging said slides inwardly toward a point between them, and rocker return springs urging said rocker mounted dies outwardly from a point between them.
 5. The combination of claim 3 wherein: said dies are shaped to pre-curl a lower edge portion of said skirt portion upon said cooperating engagement, said combination further comprising; a third die section securable to a press bolster; a first die on said third section and having a skirt confining wall, and a curling groove disposed adjacent to said wall and receiving at a reception point adjacent said wall the pre-curled lower edge portion of said skirt portion of a part formed in said first die section, said groove extending from said reception point inwardly to a termination farther from said wall; and a fourth die section aligned with said third die section and movable to cooperate with said third die section to force said pre-curled edge portion further into said groove toward said termination to finish curl said edge portion.
 6. In forming apparatus for sheet stock, the combination comprising: a first die section securable to a press; a plurality of slides on said first die section, each of said slides having a die thereon disposed inwardly with respect to a perimetrical skirt portion of a part to be formed thereon and movable outwardly against said skirt portion; a plurality of rockers on said first die section, each of said rockers having a die thereon formed to mate with one of said dies on said slides, said rockers being rockable inwardly to move said dies thereon against said skirt portion; cam follower means operable in response to movement of a press ram to cause cooperating engagement of said slide mounted dies and said rocker mounted dies with said skirt portion to form said skirt portion; a second die section aligned with said first die section and movable to cooperate with said first die section in the formation of a part therein; cam means on said second die section and engageable with said cam follower means on said slides and rockers during closure of said die sections to drive said slide mounted dies and said rocker mounted dies into skirt forming engagement with said skirt portion; said dies being shaped to pre-curl a lower edge portion of said skirt portion upon said cooperating engagement; a third die section; a first die on said third section and having a skirt confining wall, and a curling groove disposed adjacent to said wall and receiving at a reception point adjacent said wall the pre-curled lower edge portion of said skirt portion of a part formed in said first die section, said groove extending from said reception point inwardly to a termination farther from said wall; a fourth die section aligned with said third die section and movable to cooperate with said third die section to force said pre-curled edge portion further into said groove toward said termiNation to finish curl said edge portion; a press having a bolster and a ram, said first and third die sections being secured to said bolster, said second and fourth die sections being secured to a common plate drivable by said ram toward said bolster, fifth and sixth die sections secured respectively to said bolster and said common plate and co-operable to punch a blank from a sheet and draw a perimetrical skirt portion thereon during movement of said press ram; whereby as said ram moves toward said bolster, said sixth, second, and fourth die sections are closed with said fifth, first and third die sections respectively providing first, second and third stages of forming operations on a part transferable from said first to second and then to third stages, the first operation being a blank and skirt drawing operation, the second being a skirt dimpling and pre-curling operation, and the third being a finish curling operation.
 7. The combination of claim 1 wherein: the dies of said slides are disposed in a pattern with skirt forming faces thereof defining a shape having sides with elongated spaced generally parallel portions and elongated portions converging toward a rounded end at one end, and a generally straight end at the other end.
 8. The combination of claim 7 wherein: there are at least four of said slides, one on each side and one on each end, the skirt forming faces thereof defining the shape of an ironing board.
 9. The combination of claim 8 wherein: there are at least four of said rockers, one on each side and one on each end.
 10. The combination of claim 1 wherein: the dies of said slides are disposed in a pattern with skirt forming faces thereof defining a non-circular shape and having embossments therein spaced along the length thereof.
 11. The combination of claim 3 wherein said cam means include a cam member disposed between the cam follower on one of said rockers and the cam follower on one of said slides, said cam member being operable during closure of said die sections to drive away from each other the said cam followers between which said cam member is disposed and thereupon effect said co-operating engagement of the die mounted to said slide and the die mounted to said rocker with said skirt portion. 